SH25-76 and the SH25-76S tweeters: What are the construction

ATC & other manufacturers design parameters, technical queries etc
User avatar
Posts: 189
Joined: Sun Aug 30, 2015 9:47 pm
Location: UK

SH25-76 and the SH25-76S tweeters: What are the construction

Postby studioman » Sun Apr 16, 2017 8:04 pm

Does anyone know....

What are the constructional differences between the SH25-76 and the SH25-76S tweeters?

I am aware that the 76S has a more powerful magnet.
Apart from that, are the coil, dome and other details identical?

So is it the more powerful magnet that gives the 76S the improved response? Or is there more to it?

Thanks, guys.
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

User avatar
Posts: 6459
Joined: Tue Feb 23, 2010 5:46 pm
Location: Ireland

Re: SH25-76 and the SH25-76S tweeters: What are the construction

Postby MattSPL » Sun Apr 16, 2017 9:19 pm

Hi David,

I think the mid dome uses the same dome and coil, just a larger magnet and higher sensitivity in the S model. I'm guessing the tweeter is probably the same.

Cheers
Matt
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

User avatar
Posts: 189
Joined: Sun Aug 30, 2015 9:47 pm
Location: UK

Re: SH25-76 and the SH25-76S tweeters: What are the construction

Postby studioman » Sun Apr 16, 2017 10:10 pm

MattSPL wrote:Hi David,

I think the mid dome uses the same dome and coil, just a larger magnet and higher sensitivity in the S model. I'm guessing the tweeter is probably the same.

Cheers
Matt


Hi Matt. Yes, I understand that is the case with the midrange domes...

And that's what I figured was the case with the SH25-76 and 76S too....

And if it is the same dome and coil, then surely it is the different magnets which are responsible for the difference in efficiency....
ie All other things being equal (Literally...). a bigger magnet gives increased efficiency.

Does anyone else have any more info? Brad or anyone at ATC?
Thank you.
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

Posts: 408
Joined: Wed Dec 21, 2011 7:01 pm
Location: Las Vegas, Nevada, USA

Re: SH25-76 and the SH25-76S tweeters: What are the construction

Postby Brad Lunde » Sun Apr 16, 2017 11:05 pm

studioman wrote:
MattSPL wrote:Hi David,

I think the mid dome uses the same dome and coil, just a larger magnet and higher sensitivity in the S model. I'm guessing the tweeter is probably the same.

Cheers
Matt


Hi Matt. Yes, I understand that is the case with the midrange domes...

And that's what I figured was the case with the SH25-76 and 76S too....

And if it is the same dome and coil, then surely it is the different magnets which are responsible for the difference in efficiency....
ie All other things being equal (Literally...). a bigger magnet gives increased efficiency.

Does anyone else have any more info? Brad or anyone at ATC?
Thank you.


I think you guys are right, but I'll ask ti be sure. May I ask why?

Brad
Brad Lunde
Lone Mountain Audio, part of TransAudio Group
ATC Importers USA

User avatar
Posts: 189
Joined: Sun Aug 30, 2015 9:47 pm
Location: UK

Re: SH25-76 and the SH25-76S tweeters: What are the construction

Postby studioman » Mon Apr 17, 2017 8:01 pm

Just out of interest, Brad.

I have a pair of SH34-76 tweeters which of course have a different size dome. They ARE terrific. But I had asked ATC last year if I could upgrade mine to the SH25-76S. Originally I had been told I could buy them when they were available, and do the job myself, but actually I was refused recently because they now have a policy of not supplying drive units, only replacing them themselves. That would involve me carting 2 (nearly 100 kilos each) 150 litre cabs about 90 miles in a rental van, and then back again. And I have been quoted 3 hrs labour at £90 per hour. Plus 20% VAT for the government of course. Whereas I could just unbolt them and do it myself. I know I would have to tweak the HF level internally but being a retired Electronics teacher, I can do all this, I have measuring equipment.

So it just got me thinking about the 3 different ATC tweeters, the 34 and the two 25's, and what differences there were between them. I have now realised that the magnets in all three ARE all different thicknesses, same outer diameter, but different internal diameters (they are ring magnets) and different thicknesses. Possibly different grades of neodymium too, but I doubt it The magnet in the SH25-76 is, as far as I can tell, 3mm thick, the SH25-76S is 5 or 6mm thick, and my SH34-76 is 10mm thick. Also, some of the other parts are a slightly different shape (for example the rear heat treated piece varies according to which tweeter it is from)

I'm just one of those guys who likes to get an answer! OCD probably. :-)
Last edited by studioman on Fri Apr 21, 2017 4:58 pm, edited 1 time in total.
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

Posts: 408
Joined: Wed Dec 21, 2011 7:01 pm
Location: Las Vegas, Nevada, USA

Re: SH25-76 and the SH25-76S tweeters: What are the construction

Postby Brad Lunde » Tue Apr 18, 2017 4:16 am

studioman wrote:Just out of interest, Brad.

I have a pair of SH34-76 tweeters which of course have a different size dome. They ARE terrific. But I had asked ATC last year if I could upgrade mine to the SH25-76S. Originally I had been told I could buy them when they were available, and do the job myself, but actually I was refused recently because they now have a policy of not supplying drive units, only replacing them themselves. That would involve me carting 2 (nearly 100 kilos each) 150 litre cabs about 90 miles in a rental van, and then back again. And I have been quoted 3 hrs labour at £90 per hour. Plus 20% VAT for the government of course. Whereas I could just unbolt them and do it myself. I know I would have to tweak the HF level internally but being a retired Electronics teacher, I can do all this, I have measuring equipment.

So it just got me thinking about the 3 different ATC tweeters, the 34 and the two 25's, and what differences there were between them. I have now realised that the magnets in all three ARE all different thicknesses, same outer diameter, but different internal diameters (they are ring magnets). Possibly different grades of neodymium too, but I doubt it The magnet in the SH25-76 is, as far as I can tell, 3mm thick, the SH25-76S is 5 or 6mm thick, and my SH34-76 is 10mm thick. Also, some of the other parts are a slightly different shape (for example the rear heat treated piece varies according to which tweeter it is from)

I'm just one of those guys who likes to get an answer! OCD probably. :-)


After reading that, I'd take a trip to visit ATC again and meet with Rich. Its always easier to get info from someone you know and trust!

Brad
Brad Lunde
Lone Mountain Audio, part of TransAudio Group
ATC Importers USA

Posts: 267
Joined: Thu May 31, 2012 8:20 am

Re: SH25-76 and the SH25-76S tweeters: What are the construction

Postby Alexk » Fri May 05, 2017 11:05 pm

There are differences in the waveguide as well. The higher BL magnet means a naturally higher output at higher frequencies, so the change in waveguide shape compensates for this.

Or so I was told.

Return to Technical area

Who is online

Users browsing this forum: leftkath and 1 guest